Messages in this thread Patch in this message | | | Date | Thu, 16 Aug 2012 22:12:06 +0800 | From | Jeff Liu <> | Subject | [PATCH] lockdep: fix potential NULL pointer dereferences |
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Hello,
In general we can get the symbol name of a particular lock and print it out if something went wrong regarding lock/unlock stuff.
However, I observed the following info(3.5.0-rc4) when running quotacheck(1) yesterday. It has occurred only once, I can not reproduced it afterwards.
[15800.938071] quotacheck/11934 is trying to release lock ( [15800.940040] BUG: unable to handle kernel NULL pointer dereference at 0000007c [15800.940040] IP: [<c10f9b2c>] print_lockdep_cache+0x15/0x86 [15800.940040] *pde = 00000000 [15800.940040] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
Maybe something wrong at other areas, but I also noticed there is no defense for __get_key_name() failure at both __print_lock_name() and print_lockdep_cache().
How about to trigger BUG_ON() to indicate it a bit more explicit once such situation is detected?
Thanks, -Jeff
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
--- kernel/lockdep.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index ea9ee45..dfbcd86 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -508,6 +508,7 @@ static void __print_lock_name(struct lock_class *class) name = class->name; if (!name) { name = __get_key_name(class->key, str); + BUG_ON(!name); printk("%s", name); } else { printk("%s", name); @@ -538,6 +539,7 @@ static void print_lockdep_cache(struct lockdep_map *lock) if (!name) name = __get_key_name(lock->key->subkeys, str); + BUG_ON(!name); printk("%s", name); } -- 1.7.9
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